Just a quick and short post about this warning and what are possible solutions to get rid of it. So the warning happens sometimes when you setup SSL for example on Windows Sharepoint Services (WSS) site. After that, anytime you open the site, or navigate back and forth this warning pop-out.
This happens because some of links on your site point to http instead to https. So if you have some links, pictures or something else that is having http in link you have that warning. Also, what I personally experienced is that this error happened because of using specific Windows Sharepoint Services theme (Basic theme).
How to solve the problem?
Change Sharepoint theme. Go to Site actions> Site settings > Look and feel > Site theme and change theme to default.
Check if anything (links, pics…) on your site is still using http links. Change those to https or start using relative path instead of absolute. Absolute link is –> http://example.com/img.jpg and relative (in Sharepoint) is –> _layouts/images/ or //www.example.com/img.jpg
Change browser settings:
- Tools > Internet options
- Security tab > Custom level
- Scroll down to “Display mixed content” and select Enable
- Click Yes on Security warning pop-up
- Hope that solves your problem.